狂问大牛们：188, 189,192,196

knock00

狂问大牛们：188, 189,192,196

188PS: wholesale那道老机经。Wholesale price is $90, sell as 10% discount of the retail price and earn 20% profits. What’s the retailer price?
作者答案及思路：
DZ评价意见：120
更新：
那位善心人能够位我解读” sell as 10% discount of the retail price”的意思
我自己解读成: Wholesale给零售商10%的折扣
可疑的是:我的答案不是120

189Ds:  t为（r－s）的算数平方根，t、r、s为integar。问t是否有确定解。条件一r小于9，条件二t大于1
作者答案及思路：
DZ评价意见：E，注意题目，如果t,r,s为正整数，则为C
更新：算数平方根的意思是什么呢?

192PS:老机经，12个笔，3个defective，任意取3支，neither is defective 的组合有多少？
作者答案及思路：
DZ评价意见：C(3,12)
更新：
neither is defective 的意义：都没有瑕疵的吗?
如果是，那答案为何不是：Ｃ( 3,9)呢？

196PS 一数列为1/91, 1/92, …. 1/99, 1/100，问其和的范围
作者答案及思路：
DZ评价意见：(1/10,1/9)
更新：
那位大爷怎么算呢？
1/100*10 = 1/10 , 所以数列合一定大于1/10之间
请问大牛们是这样吗?

sxmeimei

以下是引用knock00在2003-12-17 22:45:00的发言：

188PS: wholesale那道老机经。Wholesale price is $90, sell as 10% discount of the retail price and earn 20% profits. What’s the retailer price?
作者答案及思路：
DZ评价意见：120
更新：
那位善心人能够位我解读” sell as 10% discount of the retail price”的意思
我自己解读成: Wholesale给零售商10%的折扣
可疑的是:我的答案不是120

Suppose the retail  price (Biao Jia) is X, then
sell as 10% discount of the retail price  means
final price is 0.9X (Shi Ji Mai Chu Jia)

So we can have: 0.9X-90=90*20% then
we can get X=120.

Sorry I can not type Chiinese now. Is this clear?

I dream to be a NN. But not right now.  

[此贴子已经被作者于2003-12-18 0:45:49编辑过]

sxmeimei

以下是引用knock00在2003-12-17 22:45:00的发言：

192PS:老机经，12个笔，3个defective，任意取3支，neither is defective 的组合有多少？
作者答案及思路：
DZ评价意见：C(3,12)
更新：
neither is defective 的意义：都没有瑕疵的吗?
如果是，那答案为何不是：Ｃ( 3,9)呢？

I agree with you. C ( 3, 9)

bestsong

0.9r/1.2=90, so r=120

bluestone1

以下是引用sxmeimei在2003-12-18 0:45:00的发言：

Suppose the retail  price (Biao Jia) is X, then
sell as 10% discount of the retail price  means
final price is 0.9X (Shi Ji Mai Chu Jia)

So we can have: 0.9X-90=90*20% then
we can get X=120.

Sorry I can not type Chiinese now. Is this clear?

I dream to be a NN. But not right now.  

[此贴子已经被作者于2003-12-18 0:45:49编辑过]

why  0.9X-90=90*20% ;  not  0.9X - 90 = 0.9X * 20% ?

the latter answer is:  X =125

sxmeimei

以下是引用bluestone1在2003-12-18 1:06:00的发言：

why  0.9X-90=90*20% ;  not  0.9X - 90 = 0.9X * 20% ?

the latter answer is:  X =125

Because the 20% profits is based on the Jin Jia ( how much you spent )
---Wholesale price.

bluestone1

以下是引用sxmeimei在2003-12-18 1:16:00的发言：

Because the 20% profits is based on the Jin Jia ( how much you spent )
  ---Wholesale price.

难道利润不是基于卖价算的吗？

困惑中。。。

bluestone1

OG 说 Gross profit is equal to revenues minus expenses, or selling price minus cost.
但没提 earn 20% profits 是基于 selling price   or    cost

catherine11

196PS 一数列为1/91, 1/92, …. 1/99, 1/100，问其和的范围
作者答案及思路：
DZ评价意见：(1/10,1/9)
更新：
那位大爷怎么算呢？
1/100*10 = 1/10 , 所以数列合一定大于1/10之间


you see that 1/90>1/91, 1/90>1/91......all together are 10 terms, so plus them we can see that 10/90>1/91.....1/100
by using the same way we also can see that 1/91...1/100>10/100.

Is it any help for you?